It hasn't been updated since 2011 but it's from the maker of vector clocks (https://www.portablefreeware.com/index.php?id=1999). Supports transparency, ability to combine screenshots, position, rotate, add reflections, 3D views, and more. It's the only freeware program I've been able to find with a "zoom" view component (like Screenpresso) in its editor:

Update: So I played with this program a bit more and find myself recommending against it. The lack of an undo function and the difficulty working with multiple objects makes this frustrating. I might use it for the nifty zoom feature but that's probably all.